With the rapid development of display technology, semiconductor element technology, as the core of display devices, has developed drastically. Among the existing display devices, as a kind of current type light emitting devices, organic light emitting diodes (OLEDs) have been applied in high performance display field more and more due to their features such as self-illumination, fast response, wide viewing angle and possibility of being manufactured on flexible substrates. OLEDs may be classified into PMOLEDs (Passive Matrix Driving OLEDs) and AMOLED (Active Matrix Driving OLEDs) according to their driving manners.
In AMOLED architecture, non-crystalline sillcon, polysilicon, oxide semiconductor, or organic thin film transistor may be used for driving. However, in a conventional process of manufacturing the above-mentioned AMOLED array substrate, a number of patterning processes is required, such as 8˜9 times of mask exposure processes. Therefore, not only the technological process is complex and cost is high, but also the overmany processing steps would result in continuous accumulation of production errors, making it difficult to guarantee the quality of AMOLED display devices.